Word Origin & History

mid-14c., "acting falsely," from un- (1) "not" + faithful. In Middle English it also had a sense of "infidel, unbelieving, irreligious" (late 14c.). Sense of "not faithful in marriage" is attested from 1828. Related: Unfaithfully; unfaithfulness.

Example Sentences for unfaithful

While men are often unfaithful to their covenant, God never is.

He would be as unfaithful to you as he has been to his trust in the bank.

It is ten times better for a woman to marry an unfaithful than a jealous husband.

It is lawful for the body to have its desires and its loves, but not to be promiscuous and unfaithful.

He wondered if it was true that there had been love between these two, and she had been unfaithful.

Unfortunately she, too, is touched by the infection of this irreverent and unfaithful age.

It was about a man who was unfaithful to his wife, and they had five children just as we have.

And at that moment I understood that I might be unfaithful to my husband.

Hadnt he said something about someones having been unfaithful to him?

When they added to the number, they feared that they were unfaithful to the original.